The present invention relates to an armature for use in a rotary electric machine and a method for manufacturing such an armature.
A large number of motors are used in various types of mechatronic products. This has resulted in a demand for motors that are more compact and inexpensive. Japanese Laid-Open Patent Publication No. 2001-298918 describes a typical armature of a motor. As shown in FIG. 12, the armature includes a core 81, which is attached to a rotary shaft 80, and a coil 82, which is wound in the core 81. The core 81 includes a base 81a and teeth 81b, which extend radially from the base 81a. Coil slots 86 are defined between adjacent teeth 81b to receive the coil 82. The coil 82 includes a plurality of bundled wires 83, which are coated with an insulative material such as enamel. The wires 83 are wound about the teeth 81b, as shown in FIG. 13. Each wire 83 is fed from a wire feeder to the core 81 via a flyer 84. The flyer 84 is then rotated to wind the wire 83 to the core 81.
However, the wire 83 has a round cross-section. This forms gaps 85, or dead space, between adjacent wires 83. It is thus difficult to increase the space factor of the coil 82. Consequently, the number of windings of each wire 83 must be increased. This requires the coil slots 86 to be enlarged, which in turn, would enlarge the core 81 and increase the size of the motor. In addition, an increase in the windings of the wires 83 on the core 81 increases manufacturing costs.